1. Field of the Invention
The present invention relates generally to methods of starting and idling an internal combustion engine for an automotive vehicle. More particularly, the present invention relates to a method for starting and idling an internal combustion engine utilizing a dynamic fuel source.
2. Description of the Related Art
Conventional fuel delivery systems for internal combustion engines adjust fuel delivered by a feedback signal created by an exhaust gas oxygen (EGO) sensor to maintain desired stoichiometric combinations. During starting and cold idling, such feedback from the EGO sensor is not available. Therefore, only open loop calculations of fuel requirements are available. A problem with open loop calculation is that such an open loop calculation will not compensate or vary as a function of the fuel blend currently being consumed. This insensitivity to fuel blend varies the operation of the internal combustion engine.
An example of an open loop system is U.S. Pat. No. 5,229,946 which discloses a method for optimizing engine performance for internal combustion engines. This method accounts for different blends of fuel; namely, pure fuels and different blends of fuel and alcohol. This method utilizes specific engine parameters to determine what type of fuel is being combusted. This method utilizes a different engine map for each blend of fuel. This approach is not flexible in that it requires a specific blend of fuel before it can look up a value in a specific map. This method also relies on sensing the amount of fuel in a fuel tank to determine whether a sensing event should even occur.
The method disclosed in U.S. Pat. No. 5,229,946 which fails to immediately determine the composition of the fuel to better enable the internal combustion engine to operate during start-up and idling situations. In fact, this disclosed method does not identify the fuel composition until the fuel tank is refilled. Further, there is no provision to measure the performance of the internal combustion engine. The method merely estimates the performance based on the last identification of fuel composition.